Bushing



Reissued Apr. 2l, 1942 EUSHING Leland J. Stevens, Baltimore, Md.,assigner to Locke Insulator Corporation, Baltimore, Md., a corporationof Maryland Original No. 2,230,194, dated January 28, 1941,

Serial No. 293,649fSeptembcr 6, 1939. Application for reissue August 29,1941, Serial No.

6 Claims.

The invention relates to bushings and more particularly to means forconnecting thereto metallic caps and/or connectors generally used withbushings for transformers and the like.

The principal object of the invention7 generally stated, is to provide abushing cap which may be so connected to a bushing as to provide a fluidand gas tight joint therebetween, said joint serving to prevent leakagefrom or into said bushing.

Another object of the invention is to provide a simple form of bushingwhich may be connected to the electrical apparatus for which it isdesigned in any one of a number of ways and which is provided with a capsealing the interior of said bushing, said cap having formed therein anopening, the side edges of which are adapted to cooperate With theelectrical connector for maintaining 'the same against rotation withrespect of both cap and bushing.

A still further object of the invention is to provide a simple, strongand inexpensive means for rigidly and permanently Securing a metalliccap to a bushing, said means being adapted to prevent relative rotationbetween the cap and bushing.

Other objects of the invention will appear from the detailed descriptionthereof, especially when taken in connection with the accompanyingdrawing in which,

Figure 1 is an elevational view partially in section, illustrating abushing and means for clamping the same to the transformer or otherelectrical apparatus.

Figure 2 is a 'top plan view of the structure shown in Figure 1.

Figure 3 is a central vertical section of Fig-A ure 1.

Throughout the specification and drawing like parts are designated bylike reference characters.

Before describing the preferred embodiment of the invention which I haveillustrated, it is believed it will lead to a better understanding ofthe invention to describe the general conditions now existing in thisparticular branch of theelectrical art.

Manufacturers of electrical apparatus such as transformers usingentrance or lead-in bushings generally provide their own characteristicmeans for connecting the bushing to the apparatus. This practicenecessitates the bushing manufacturers providing a large number oi'alternate styles of bushings so as to provide a bushing which willcooperate with the different types of fastening or securing meansutilized by the bushing manufacturers. The result has been that thebushing manufacturers are required to keep in stock various styles ofbushings or to keep in stock molds from which these bushings ofdifferent styles may be manufactured. It has been found, however, thatby changing the external shape of the bushing to the form illustrated inthe accompanying drawing it is possible to use a single style of bushingwith a number o different makes of transformers.

The problem'outlined above is only one of the problems which theinsulator or bushing manufacturer has to face in connection with theproduction of these bushings. It is of course essential that theconnection between the line conductor and the lead-in conductor orelectrical connector be rigidly maintained in respect of the bushing andits cap and 'that the connection between the line conductor and/or theelectrical connector carried by the bushing be maintained againstrotation in respect of the bushing at the time of connection and duringthe subsequent use of the apparatus. It has therefore been customaryeither to counter-bore the bushing and/ or to provide the same with akey-way so that the metallic connector7 when inserted in the bushing,would cooperate with the shaped portion of the recess or the key-way soas to be maintained against rotation with respect of the bushing. It isexceedingly difficult and expensive to counterbore or to cut key-ways inthe clay since these operations can be performed only after the clay hasarrived at either the leather or bone dry state and such manipulation ofclay in the leather or bone dry state is apt to cause incipient crackswhich do not show until after the piece has been finished or fired.

Referring now to the embodiment of the invention, the numeral Iydesignates generally a leadin or entrance bushing adapted to be rigidlyconnected to a portion of the housing 2 of artransformer or otherelectrical apparatus 3. This type of bushing is preferably produced bythe extrusion process, the clay from the pug mill being forced throughthe nozzle of the pug mill and formed into a hollow column or pipe, themaximum diameter of which is slightly greater than the maximum diameterof the finished bushing measured over the petticoat 4. After the clayhas been formed as a hollow column and allowed to dry it is placed in alathe or other machine and the petticoats 4, 5, 5 and l, as well as theflange 8 and the head El, are turned thereon. It will be understood thatthe number of petticoats may be altered as desired and that if desiredthe opposite end of the bushing may also be formed with a head similarto the head 9. The flange 8 is undercut, as at I0, to form a downwardlyfacing recess II into which a washer I2 is adapted to fit, the washer inturn resting, when the parts are in assembled position, upon a flange I3formed around the opening I4 in the transformer housing. I haveillustrated the bushing as being con nected to the transformer by aplurality of J clips I5, each of which is provided in the leg IB with anopening II through which the bolt I8 is adapted to project. The otherleg I9 of each clip is provided with a notch 2D adapted to embrace theadjacent side of the bolt I8, the leg IE of the clip being adapted tooverlie the flange 8 and the clips are maintained in tight engagementwith the flange by means of the nuts 2l which are screw-threadedlyconnected to the bolts I8, It will thus be seen that by applyingpressure to the clips I the washer or gasket I2 is forced into tight andintimate contact with the flange B of the bushing and flange I3 of thetransformer housing forming a leakeproof connection between the'bushingand the transformer.

The head 9 is provided at its lower portion with an undercut shoulder22, the purpose and object of which will be hereinafter described. Inthe event that a metallic connector such as 23 is to be employed thesame is adapted to extend through a metal cap 24 and is provided at itsupper end with a threaded portion 25 having an opening 2B therein intowhich the line conductor is adapted to extend and by which the conductoris secured to the connector by means of the nuts 21 and 28 and the locknut 29. Slidably received on the connector 23 between the shoulderportion 3U and the nut 28 and adapted to overlie the cap 24 is ametallic washer 3|, the latter being adapted to house a compositionwasher 32, the latter preferably being formed of felt or like material.

It will be understood from the drawing, particularly Figure 3, thatinterposed between the cap 24, and the upper end of the bushing 9 Iprovide another washer 33 preferably of compressible material such ascork, rubber, felt or the like. The opening 34 in the cap 24 isnon-circular in outline and is adapted to it the adjacent portion of theconnector 23 so as to maintain the cap and connector against relativerotation when the parts are in fully assembled position. The head 9 ofthe bushing is provided with a roughened surface 9a which can beproduced in any one of a number of ways, the simple method being toprovide a sanded surface which, during the firing of the bushing becomesfirmly attached to the underlying surface of the bushing head. Thisroughened surface of the head, the inner surface of the cap and thewasher 33 are coated with red Glyptol or other suitable lacquer, shellacor varnish as desired. The parts are then assembled and pressure isapplied to the cap until the washer 33 is compressed to substantiallyone-half its original thickness. When the parts are maintained in thisposition the downwardly extending ange 35 of the cap 24 is then rolledor crimped so as to cause the inner surface to engage the undercutshoulder 22 of the head. Pressure is then released `and the expansion ofthe washer forces the shoulder formed on the flange 35 against theshoulder 22 so as to provide an exceedingly tight joint and as soon asthe Glyptol, shellac or varnish has dried or set the cap is maintainedin xed position with reference to the bushing by a connection whichrequires practically destructive effort to break.

By utilizing a washer of the composition named or one of similarmaterial it is possible to pro-` vide both a fluid and gas tight jointbetween the cap and its associated partsand the bushing. The jointbetween the shoulder 22 and the flange 35 is rolled tightly initiallyand on release of the external force the Washer forces the adjacentfaces into tight engagement, and in this position the parts are sealedby the setting or hardening of the varnish or other compound. In theevent the cap is perforated for the reception of the stem 23 I havefound that the compressed washer will flow so as to embrace the saidstem and vform a gas and fluid tight joint.

The washer 32 serves to prevent the entry of moisture into the bushingand the bushing is now finished and ready for connection to atransformer or other electrical apparatus.

I claim:

1. In combination with a bushing having a bulbous head, the lowerinclined underlying surface of said head being roughened, of a metalliccap provided with a deformable skirt portion adapted to fit over saidhead, a compressible composition washer adapted to fit between the topof said cap and the upper surface of said head, means for adhesivelysecuring together said head, washer and cap, said means comprising alacquer, and means for connecting said cap and bushing, said last namedmeans comprising the deformable skirt portion, said means serving tomaintain said washer under compression, said washer also serving tomaintain direct contact between said deformable portion of said skirtand said inclined surface of said bushing.

2. An entrance bushing for transformers and the like wherein the bushingis exteriorly formed with an undercut head having an outwardly inclinedunderlying surface, and a plurality of spaced petticoats positionedbelow said surface, said bushing being interiorly formed with alongitudinal bore, the combination of a single piece cap having the topaperture in alinement with said bore, a deformable peripheral flangedepend ing from said top portion and adapted to be directly engaged withthe outwardly inclined surface of said head, a compressed resilientwasher interposed between said top portion and the adjacent surface ofsaid head and forming a seal at the upper surface of said head, meansfor adhesively securing together said head, washer and cap, said washerbeing apertured in alinement with said cap aperture, a metallicconnector having an inner portion within said bore, and a stemprojecting through said cap and washer apertures, a flange on saidconnector underlying the adjacent portion of said washer, and removablemeans associated with said stem for drawing said connector upwardly tobring said fiange and washer into engagement, the non-circular portionof said connector entering a like opening in said cap for maintainingsaid connector in a xed non-rotatable position when the parts areassembled.

3. An entrance bushing for transformers and the like wherein the bushingis exteriorly formed with an undercut head and a longitudinal bore, thecombination of a cap, portions of which interlockingly` engage with theundercut portion of said head, said cap having a non-circular openingtherein, a compressible resilient washer having a centrally disposedopening therein interposed between said cap and the upper surface ofsaid head, means for adhesively securing together said head, washer andcap, saidv washer forming a seal, said washer also serving to maintainsaid interlocking portions of said cap in engagement with said head, ametallic connector provided with an inner portion positioned within saidbore, said portion having a non-circular portion, and a stem extendingthrough said apertures in said cap and washer, and means movablyassociated with said connector stem for drawing the same upwardly toengage said portion within the noncircular opening in said cap forpreventing rotation of said connector when the parts are assembled.

4. An entrance bushing for transformers and the like wherein the bushingis exteriorly formed with a head adjacent one extremity thereof, thesurface of said head forming the base of a truncated cone-shaped portionof said bushing, the latter also having a central longitudinal bore, thecombination of a cap having a deformable skirt portion and a topportion, the latter being provided with an aperture therein, said topbeing spaced from the upper surface of said head, an apertured resilientwasher interposed between said apertured top portion and said last namedsurface, said deformable skirt portion being adapted to directlyinterlock with said cone-shaped surface to retain said resilient Washerunder a predetermined compression, a metallic connector having the innerportion thereof positioned within said bore and having portions bearingagainst said resilient washer, said connector having its stem extendingthrough said cap and washer apertures, resilient means surrounding saidstem and positioned above said cap, and means rotatably associated withsaid connector stem for maintaining said connector in engagement withsaid washer and said resilient means in engagement with said cap.

5. The combination with a bushing generally circular in cross section,said bushing having a portion of increased diameter, a iiat faceconnecting the periphery of said portion with the body of the bushing, ametallic member embracingly engaging said portion, said member beingprovided with a flat portion positioned adjacent said face and beingfurther provided with a deformable skirt portion positionedsubstantially at right angles to the plane of said flat face, acompressible elastic washer interposed between the face of said enlargedportion and the adjacent corresponding portion of said member, theopposite end of said enlarged portion being connected to the body of thebushing by an inclined surface of revolution spaced from said irst namedface, means for adhesively securing said face, washer and metallicmember, and additional means for connecting said metallic member andbushing against separation, said means comprising the deformable skirtportion, said means when deformed engaging said inclined surface andserving to maintain said washer under compression, the elasticity ofsaid Washer also serving to maintain a direct contact between thedeformed portion of said skirt and said inclined surface.

6. The combination with a bushing generally circular in cross section,said bushing having a portion oi' increased diameter, the periphery ofone end of said enlarged portion being joined to the body of the bushingby a face disposed at right angles to the longitudinal axis of thebushing, a metallic member having a flat base, a skirt projecting fromsaid base and forming therewith a cup, the diameter of said cup beinglslightly `greater than the diameter of the enlarged portion of saidbushing, an inclined wall formed as a surface of revolution connectingthe opposite end of said enlarged portion with the body of 'saidbushing, said metallic cup being adapted to embrace said enlargedportion of said bushing, a washer interposed between the base of saidcup and said face of said bushing, means for adhesively securing theopposite faces of said Washer to said bushing and to the base of saidcup, and means for maintaining said Washer under compression and forconnecting said cup and bushing against separation, said meanscomprising deforming the free edge of said cup to cause all portionsthereof to engage with adjacent portions of said inclined wall of theenlarged portion of the bushing.

LELAND J. STEVENS.

